There are 36 recalls as of June 19 2014. The next highest recalls were in 2000 & 1994 at 53 recalls. If the pace of the first half of 2014 continues, GM could beat the previous highs by a wide margin.
Note: There has been some media coverage that there have been 48 recalls so far in 2014. But those figures are counting different phases of the same recall separately, whereas the NHTSA considers it as one issue. For E.g. the ignition switch issue has been counted separately by some parts of the media on 25th Feb, March 28th & April 9th separately.