Last April, Microsoft (MSFT -1.27%) CEO Satya Nadella declared that the tech giant's annual cloud revenue would reach $20 billion by the end of fiscal 2018. That growth could help Microsoft transform its aging Windows and Office cash cows from packaged software into cloud-based services, and expand its digital moat against rival cloud ecosystems. Let's discuss how that key business performed last quarter with four simple numbers.

Microsoft CEO Satya Nadella. Source: Microsoft.

1. Annual run rate: Over $9.4 billion
Microsoft reported that the annual run rate of its commercialized cloud business exceeded $9.4 billion last quarter -- a 15% jump from the first quarter and a 71% increase from a year earlier. Most of that revenue comes from SaaS (software as a service) platforms like Office 365 and Dynamics CRM. A smaller percentage comes from its IaaS/PaaS (infrastructure/platform as a service) "cloud platform" Azure.

Azure is the most closely watched part of Microsoft's cloud business, since IaaS/PaaS platforms are expected to grow at a faster rate than SaaS ones. A recent Technology Business Research report estimates that the global SaaS market will grow at a compound annual growth rate (CAGR) of just 8.1% between 2015 and 2018. Goldman Sachs estimates the the IaaS/PaaS market will grow at a 19.6% CAGR during that same period.

2. Azure's revenue growth: 140%
Microsoft reported that Azure's revenues rose 140% annually on a constant currency basis last quarter, although it didn't disclose an exact revenue figure. Nonetheless, that sounds comparable to the first quarter, when Azure revenue "more than doubled year-over-year".

Last October, Forrester Research estimated that Azure had an annual run rate of $1.6 billion, which would make it the second largest IaaS/PaaS platform in the world after Amazon's (AMZN -2.56%) AWS. Last quarter, Amazon reported that AWS had an annual run rate of almost $10 billion.

Azure represents the cloud backbone of Microsoft's digital ecosystem. Major services like Dynamics, Cortana, Bing, and Office 365 are already integrated with the cloud platform. That integration casts a halo effect on Azure's growth. During last quarter's conference call, Nadella claimed that "Azure customers who purchase Office 365 consume eight times more Azure than other customers."

3. Office 365 consumer subscribers: 20.6 million
Speaking of Office, Microsoft reported that its number of Office 365 consumer subscribers rose 124% annually to 20.6 million last quarter. That growth complemented Office 365's 70% constant currency sales growth on the enterprise front.

Source: Microsoft.

Those numbers suggest that Microsoft's plan to transition away from periodic updates for Office to an evergreen subscription-based model is paying off. They also indicate that fears about Alphabet's (GOOG -1.10%) (GOOGL -1.23%) free productivity apps might be overblown. Alphabet remains a niche player in that market -- Google Drive for Work, its beefed up productivity suite for businesses, had just over a million paying customers last October.

However, investors should note that Microsoft doesn't disclose exact revenue figures for Office 365. This makes it tough to gauge the financial impact of the free trial versions which have been liberally bundled with new tablets, 2-in-1 devices, and PCs.

4. Dynamics revenue growth: 11%
Dynamics revenue rose 11% on a constant currency basis, down slightly from 12% growth in the first quarter. However, its installed base posted "triple-digit" growth for the fifth consecutive quarter.

Looking ahead, Microsoft's Dynamics could have a tough time competing against Salesforce (CRM -0.57%), the 800-pound gorilla in the CRM market. Salesforce claims that its global market share rose from 10.6% to 18.4% between fiscal 2011 and 2015. Microsoft, the fourth largest CRM player, only grew its share from 5.7% to 6.2% during that period. The integration of Dynamics into Azure and Windows 10 could boost Microsoft's CRM market share among enterprise customers, but it's still a long uphill battle.

Should Microsoft be more transparent?
Microsoft's cloud figures have always been "cloudy", since it replaces clear figures like revenue and margins with annual run rates, year-over-year growth figures, and subscriber growth. Last December, former Microsoft CEO Steve Ballmer told Bloomberg that he believed that the company should reveal the revenue and margins of its cloud businesses. "It's sort of a key metric," said Ballmer. "If they talk about it as key to the company, they should report it."

Last year, Amazon cleared up a lot of speculation about AWS by reporting the business' sales and operating income every quarter. If Microsoft follows Amazon's example, investors can gain a clearer picture of how important each of these businesses actually is.