Hi, my database is (partially) the following:

Code:
* Example generated by -dataex-. For more info, type help dataex
clear
input float year_quarter str6 route str3 carrier float(rival overlap postmerger)
208 "ABECLT" "US" 0 0 0
209 "ABEMCO" "F9" 0 0 0
200 "ABEMCO" "FL" 0 0 0
201 "ABEMCO" "FL" 0 0 0
202 "ABEMCO" "FL" 0 0 0
203 "ABEMCO" "FL" 0 0 0
204 "ABEMCO" "FL" 0 0 0
205 "ABEMCO" "FL" 0 0 0
206 "ABEMCO" "FL" 0 0 0
207 "ABEMCO" "FL" 0 0 0
208 "ABEMCO" "FL" 0 0 0
209 "ABEMCO" "FL" 0 0 0
200 "ABEMCO" "G4" 0 0 0
201 "ABEMCO" "G4" 0 0 0
202 "ABEMCO" "G4" 0 0 0
203 "ABEMCO" "G4" 0 0 0
204 "ABEMCO" "G4" 0 0 0
212 "ABESFB" "G4" 0 0 1
213 "ABESFB" "G4" 0 0 1
214 "ABESFB" "G4" 0 0 1
215 "ABESFB" "G4" 0 0 1
216 "ABESFB" "G4" 0 0 1
217 "ABESFB" "G4" 0 0 1
218 "ABESFB" "G4" 0 0 1
219 "ABESFB" "G4" 0 0 1
220 "ABESFB" "G4" 0 0 1
221 "ABESFB" "G4" 0 0 1
222 "ABESFB" "G4" 0 0 1
223 "ABESFB" "G4" 0 0 1
209 "ABQATL" "AA" 1 0 0
208 "ABQATL" "DL" 1 0 0
209 "ABQATL" "DL" 1 0 0
210 "ABQATL" "DL" 1 0 0
211 "ABQATL" "DL" 1 0 0
209 "ABQBWI" "AA" 1 0 0
205 "ABQBWI" "WN" 1 0 0
206 "ABQBWI" "WN" 1 0 0
208 "ABQBWI" "WN" 1 0 0
209 "ABQBWI" "WN" 1 0 0
210 "ABQBWI" "WN" 1 0 0
211 "ABQBWI" "WN" 1 0 0
213 "ABQBWI" "WN" 1 0 1
214 "ABQBWI" "WN" 1 0 1
217 "ABQBWI" "WN" 1 0 1
218 "ABQBWI" "WN" 1 0 1
221 "ABQBWI" "WN" 1 0 1
222 "ABQBWI" "WN" 1 0 1
200 "ABQDAL" "WN" 0 0 0
201 "ABQDAL" "WN" 0 0 0
202 "ABQDAL" "WN" 0 0 0
203 "ABQDAL" "WN" 0 0 0
204 "ABQDAL" "WN" 0 0 0
205 "ABQDAL" "WN" 0 0 0
206 "ABQDAL" "WN" 0 0 0
207 "ABQDAL" "WN" 0 0 0
208 "ABQDAL" "WN" 0 0 0
209 "ABQDAL" "WN" 0 0 0
210 "ABQDAL" "WN" 0 0 0
211 "ABQDAL" "WN" 0 0 0
212 "ABQDAL" "WN" 0 0 1
213 "ABQDAL" "WN" 0 0 1
214 "ABQDAL" "WN" 0 0 1
215 "ABQDAL" "WN" 0 0 1
216 "ABQDAL" "WN" 0 0 1
217 "ABQDAL" "WN" 0 0 1
218 "ABQDAL" "WN" 0 0 1
219 "ABQDAL" "WN" 0 0 1
220 "ABQDAL" "WN" 0 0 1
221 "ABQDAL" "WN" 0 0 1
222 "ABQDAL" "WN" 0 0 1
223 "ABQDAL" "WN" 0 0 1
204 "ABQDEN" "CO" 0 0 0
205 "ABQDEN" "CO" 0 0 0
206 "ABQDEN" "CO" 0 0 0
207 "ABQDEN" "CO" 0 0 0
200 "ABQDEN" "F9" 0 0 0
202 "ABQDEN" "F9" 0 0 0
206 "ABQDEN" "F9" 0 0 0
207 "ABQDEN" "F9" 0 0 0
211 "ABQDEN" "F9" 0 0 0
213 "ABQDEN" "F9" 0 0 1
214 "ABQDEN" "F9" 0 0 1
215 "ABQDEN" "F9" 0 0 1
216 "ABQDEN" "F9" 0 0 1
202 "ABQDEN" "UA" 0 0 0
208 "ABQDEN" "UA" 0 0 0
221 "ABQDEN" "UA" 0 0 1
223 "ABQDEN" "UA" 0 0 1
200 "ABQDEN" "WN" 0 0 0
201 "ABQDEN" "WN" 0 0 0
202 "ABQDEN" "WN" 0 0 0
203 "ABQDEN" "WN" 0 0 0
204 "ABQDEN" "WN" 0 0 0
205 "ABQDEN" "WN" 0 0 0
206 "ABQDEN" "WN" 0 0 0
207 "ABQDEN" "WN" 0 0 0
208 "ABQDEN" "WN" 0 0 0
209 "ABQDEN" "WN" 0 0 0
210 "ABQDEN" "WN" 0 0 0
211 "ABQDEN" "WN" 0 0 0
end
format %tq year_quarter

I would like to count the number of routes, without repetition, for which overlap = 1. I can only count the total number of observation of overlap by firms. Thank you!

Tommaso