Most 5 set matches at a Grand Slam tournament in the Open Era?

Question

What is the record for the most number of five-set matches at a Grand Slam tournament in the Open Era?
Where does the 2019 US Open (27 five-set matches) rank in the all-time list?

Answer 1

According to the data provided by Jeff Sackmann, these are the Grand Slams with the most 5 setters since 1969:

1969    Wimbledon       34
1983    US Open         34
2004    US Open         34
1992    Roland Garros   33
1994    Wimbledon       33
2001    Roland Garros   33
2010    Wimbledon       33
2012    Wimbledon       32
1976    Roland Garros   31
1998    Australian Open 31
2001    Wimbledon       31
2015    Wimbledon       31

This year's US open would rank only 36th in that list.