I've created a few charts that look at the number of priests and members of religious orders over the last several decades. To avoid it looking like spaghetti, I only used the top dozen orders based on number of priests*. I also split the top 4 from the other 8 - there is very little overlap between the two and it makes the charts much clearer.
The charts are posted here. (.pdf format)
The Jesuits were the first order (of the top dozen) to have lost more than half of their members from their recent high point (from 36,038 in 1966 to 17,908 in 2011).
Three more orders are very close to reaching that point: Oblates of Mary Immaculate (down 49%), Franciscans (down 48%), and Vincentians/Lazarists (down 46%). But the last two of those showed small gains in the last year.
In terms of priests, no order has reached that point yet and the only one really close is Benedictines which are down 48% from their recent high point (from 7,058 in the early 1970s to 3,692 in 2014).
In the top dozen, only one order, Divine Word Missionaries, has hit its high mark in terms of members in recent years (6,131 in 2009).
In terms of priests, two orders hit their highest mark in 2014: Divine Word Missionaries with 4,202 and Discalced Carmelites with 2,880.
(* Out of curiosity I checked the top dozen orders based on number of members - it was the same dozen, but in a slightly different order.)
Note that only Male Religious Orders were included because that happens to be the data I have readily available. As time permits, I'll try to do similar charts for Female Religious Orders.