Don't know how to dispense with the counting, but you can count by the screenful, rather by individual cities.
Try Mercator's way with a slight modification. Count the number of times you click large increment scrolls down until you reach the bottom of the list. Multiply that number by 15 and add the number of cities on the last screen's list.
e.g. Say I've got 97 cities.
- First screen: cities 1-16
- 2nd screen: 16-31
- Third: 31-46
- Fourth: 46-61
- Fifth: 61-76
- Sixth: 76-91
- Last: 91-97
Takes six clicks to increment from beginning to end and last page has 7 cities. So, 6x15+7=97.
Oddly it works differently if you press [Page Down] instead of clicking.
- First screen: cities 1-16
- 2nd screen: 2-17
- Third: 18-33
- Fourth: 34-49
- Fifth: 50-65
- Sixth: 66-81
- Last: 82-97
Takes six PgDn's: 6x16 + 1 = 97.
Does any of this make sense?