Funny, but alternative facts.
Utd actually:
27.11.2013 Bayer 04 Leverkusen 0:5 (Champions League, under Moyes no less. Leverkusen should be ashamed)
18.03.2012 Wolverhampton Wanderers 0:5 (Premier League)
City (PL only since March 18, 2012):
14.04.2012 Norwich City 1:6
17.11.2012 Aston Villa 5:0
02.11.2013 Norwich City 7:0
24.11.2013 Tottenham Hotspur 6:0
22.03.2014 Fulham FC 5:0
21.02.2015 Newcastle United 5:0
10.05.2015 Queens Park Rangers 6:0
03.10.2015 Newcastle United 6:1
06.05.2017 Crystal Palace 5:0
21.05.2017 Watford FC 0:5
09.09.2017 Liverpool FC 5:0
16.09.2017 Watford FC 0:6
23.09.2017 Crystal Palace 5:0
14.10.2017 Stoke City 7:2
22.04.2018 Swansea City 5:0
19.08.2018 Huddersfield Town 6:1
City (all competitions since November 27, 2013):
08.01.2014 West Ham United 6:0 (EFL Cup)
15.01.2014 Blackburn Rovers 5:0 (FA Cup)
22.03.2014 Fulham FC 5:0 (League)
24.09.2014 Sheffield Wednesday 7:0 (EFL Cup)
21.02.2015 Newcastle United 5:0 (League)
10.05.2015 Queens Park Rangers 6:0 (League)
03.10.2015 Newcastle United 6:1 (League)
16.08.2016 FCS Bucharest 0:5 (Champions League)
06.01.2017 West Ham United 0:5 (FA Cup)
06.05.2017 Crystal Palace 5:0 (League)
21.05.2017 Watford FC 0:5 (League)
09.09.2017 Liverpool FC 5:0 (League)
16.09.2017 Watford FC 0:6 (League)
23.09.2017 Crystal Palace 5:0 (League)
14.10.2017 Stoke City 7:2 (League)
22.04.2018 Swansea City 5:0 (League)
19.08.2018 Huddersfield Town 6:1 (League)
So only the 16 in the Premier League and 17 across all competitions then since the respective Utd result.