In 2010 I attempted to estimate the impact of Trip, the results can be seen here, but the important point was an estimate that 40.77% of searches improve patient care. Within that post I discussed why the 40.77% might be too high and why it might be too low – there are good reasons on both sides.
In 2013 Trip was searched 4 millions times. So, 40.77% = 1,630,800.
Bottom line: in 2013 Trip helped improve patient care over 1.6 million times.
Oh yes, we were also mentioned in over 350 systematic reviews and/or articles (see here).