Using cypher from Neo4j, how would I calculate the average year of birth of those users called 'Subscribers'?

start_time stop_time trip_duration start_station_id start_station_name 01/05/2019 06:29 01/05/2019 06:57 1679 3697 W 64 St & Thelonious Monk Circle 01/05/2019 06:34 01/05/2019 06:54 1184 3140 1 Ave & E 78 St 01/05/2019 06:43 01/05/2019 06:46 184 3151 E 81 St & York Ave 01/05/2019 06:53 01/05/2019 07:01 483 3169 Riverside Dr & W 82 St 01/05/2019 07:01 01/05/2019 07:02 81 2003 1 Ave & E 18 St 01/05/2019 07:02 01/05/2019 07:13 681 327 Vesey Pl & River Terrace 01/05/2019 07:10 01/05/2019 07:18 481 410 Suffolk St & Stanton St 01/05/2019 07:15 01/05/2019 07:23 476 366 Clinton Ave & Myrtle Ave 01/05/2019 07:19 01/05/2019 07:30 624 515 W 43 St & 10 Ave 01/05/2019 07:27 01/05/2019 07:32 256 326 E 11 St & 1 Ave 01/05/2019 07:31 01/05/2019 07:41 624 3140 1 Ave & E 78 St 01/05/2019 07:36 01/05/2019 07:57 1264 410 Suffolk St & Stanton St 01/05/2019 07:39 01/05/2019 07:41 123 3151 E 81 St & York Ave 01/05/2019 07:47 01/05/2019 07:58 629 346 Bank St & Hudson St 01/05/2019 07:50 01/05/2019 08:02 715 3140 1 Ave & E 78 St 01/05/2019 07:52 01/05/2019 08:09 1032 545 E 23 St & 1 Ave start_station_latitude start_station_longitude stop_station_id stop_station_name 40.77515953 -73.98918696 327 Vesey Pl & River Terrace 40.77140426 -73.9535166 3140 1 Ave & E 78 St 40.7728384 -73.94989233 3140 1 Ave & E 78 St 40.78720869 -73.98128127 3697 W 64 St & Thelonious Monk Circle 40.73381219 -73.98054421 2003 1 Ave & E 18 St 40.7153379 -74.01658354 3472 W 15 St & 10 Ave 40.72066442 -73.98517977 257 Lispenard St & Broadway 40.693261 -73.968896 3440 Fulton St & Adams St 40.76009437 -73.99461843 522 E 51 St & Lexington Ave 40.72953837 -73.98426726 2003 1 Ave & E 18 St 40.77140426 -73.9535166 3132 E 59 St & Madison Ave 40.72066442 -73.98517977 522 E 51 St & Lexington Ave 40.7728384 -73.94989233 3151 E 81 St & York Ave 40.73652889 -74.00618026 327 Vesey Pl & River Terrace 40.77140426 -73.9535166 3132 E 59 St & Madison Ave 40.736502 -73.97809472 522 E 51 St & Lexington Ave stop_station_latitude stop_station_longitude 40.7153379 -74.01658354 40.77140426 -73.9535166 40.77140426 -73.9535166 40.77515953 -73.98918696 40.73381219 -73.98054421 40.74275383 -74.00747359 40.71939226 -74.00247214 40.69241829 -73.98949474 40.75714758 -73.97207836 40.73381219 -73.98054421 40.76350532 -73.97109243 40.75714758 -73.97207836 40.7728384 -73.94989233 40.7153379 -74.01658354 40.76350532 -73.97109243 40.75714758 -73.97207836 L M N bike_id user_type birth_year gender trip_id 33882 Subscriber 1958 2 0 30766 Subscriber 1967 2 1 34246 Subscriber 1992 1 2 16250 Subscriber 1952 2 3 25149 Subscriber 1963 1 4 29186 Subscriber 1980 1 5 32893 Subscriber 1979 1 6 20168 Subscriber 1988 2 7 26072 Subscriber 1987 2 8 21002 Subscriber 1967 1 9 20182 Subscriber 1995 1 10 17231 Subscriber 1994 1 11 26349 Subscriber 1941 1 12 30034 Subscriber 1994 1 13 35175 Subscriber 1987 2 14 18909 Subscriber 1982 1 15 1