Table:
text: List of windmills in Hertfordshire
Locations
C
Location_ Name_of_mill_and_grid_reference Type_ Maps First_mention_or_built Last_mention_or_demise_
Chesfield  Post  1318 1372
Chesfield Chesfield Park Titt iron wind engine  1896 
Cheshunt TL 317 036 Post  1843 Demolished c. 1860
Cheshunt Goff`s Oak Mill , TL 317 036 Tower  c. 1860 Demolished 1953
Cheshunt Turner`s Hill Mill , TL 363 023  1822 1822 1861
Chipperfield TL 037 014 Post  1594 1594
Chipperfield TL 037 014 Smock 1822 1822 1881, gone by 1896
Chipping Approximately , TL 350 319 Post 1720 , 1728 1720 1728
Clothall Approximately , TL 264 326 Post  1370 1370
Codicote Codicote Heath , Approximately , TL 206 185 Smock  1841 1855, gone by 1881

text: List of windmills in Hertfordshire
Locations
C
Location_ Name_of_mill_and_grid_reference Type_ Maps First_mention_or_built Last_mention_or_demise_
Colney Heath Colney Heath Mill , TL 205 055 Tower  1854 Windmill World
Cottered  Post  1581 1581
Cromer    1192 1576
Cromer Cromer Mill , TL 304 286 Post 1720 , 1728 , 1749 , 1766 , 1800 , 1822 1720 Windmill World
Croxley Green Croxley Green Mill , TQ 067 953 Tower  c. 1860 Windmill World

Question: How many windmills were there in Hertfordshire?