The midstream industry is having a great 2013, and many companies in this energy subsector are outperforming the S&P 500. In this video, Motley Fool contributor Aimee Duffy takes a look at the three top performers through the first quarter of 2012. All three companies grew their respective share prices by at least 30%; they make for three great places to start researching the next company to add to your portfolio.