RISP Averages

The table below runs through the last 24 years to calculate 1) what percentage of runs are scored in situations with runners in scoring position and 2) what is the percentage of plate appearances that result in runners in scoring position? According to the table below and after tabulating all 24 years of data the two RISP averages are;  #1 is almost exactly 3/4 and  #2 is almost exactly 1/3.

Year RISP Runs # Runs % RISP PAs # PAs %
1990 13859 17919 0.77 52681 160316 0.33
1991 13994 18128 0.77 52186 160746 0.32
1992 13534 17341 0.78 52807 160545 0.33
1993 16149 20862 0.77 58151 174564 0.33
1994 11866 15751 0.75 41791 124483 0.34
1995 14864 19554 0.76 52496 156703 0.34
1996 17165 22832 0.75 59086 177261 0.33
1997 16256 21602 0.75 58218 175541 0.33
1998 17589 23296 0.76 62816 188280 0.33
1999 18498 24690 0.75 63963 189692 0.34
2000 18639 24969 0.75 63801 190261 0.34
2001 17007 23199 0.73 60788 186976 0.33
2002 16884 22408 0.75 61084 186615 0.33
2003 17200 22978 0.75 61237 187449 0.33
2004 17342 23376 0.74 61806 188539 0.33
2005 16711 22325 0.75 60363 186292 0.32
2006 17575 23599 0.74 61943 188071 0.33
2007 17732 23322 0.76 62470 188623 0.33
2008 16944 22585 0.75 61270 187631 0.33
2009 16763 22419 0.75 61202 187079 0.33
2010 16074 21308 0.75 60062 185553 0.32
2011 15564 20808 0.75 58949 185245 0.32
2012 15285 21016 0.73 57609 184179 0.31
2013 14874 20255 0.73 57110 184873 0.31
TOTAL 388368 516542 0.75 1403889 4285517 0.33