Scraping table result "null" on some column

Hello.

I'm trying to parse this table on this site.
http://www.aviationfanatic.com/ent_list.php?ent=4
The table is very simple but I got a lot of data with "null"... I think the cause if the 2 last rows (sum rows) which are duplicated, but I don't know how to tell to web scraper to ignore them.

Can you help me ?

My sitemap is here :
{"_id":"planes","startUrl":["http://www.aviationfanatic.com/ent_list.php?ent=4"],"selectors":[{"id":"table","type":"SelectorTable","parentSelectors":["_root"],"selector":"table","multiple":true,"columns":[{"header":"#","name":"#","extract":false},{"header":"Aircraft type ID","name":"Aircraft type ID","extract":true},{"header":"Manufacturer name","name":"Manufacturer name","extract":true},{"header":"Aircraft type name","name":"Aircraft type name","extract":true},{"header":"# of related pictures","name":"# of related pictures","extract":true},{"header":"ICAO aircraft type designator","name":"ICAO aircraft type designator","extract":true},{"header":"Manufacturer country","name":"Manufacturer country","extract":true},{"header":"Category","name":"Category","extract":true},{"header":"Role","name":"Role","extract":true},{"header":"Engine type","name":"Engine type","extract":true},{"header":"Engines","name":"Engines","extract":true},{"header":"WTC","name":"WTC","extract":true},{"header":"Seats","name":"Seats","extract":true},{"header":"First flight","name":"First flight","extract":true},{"header":"Last manufactured","name":"Last manufactured","extract":true},{"header":"Total # built","name":"Total # built","extract":true},{"header":"Info (external)","name":"Info (external)","extract":true},{"header":"# of aircraft in DB","name":"# of aircraft in DB","extract":true},{"header":"# of related collections","name":"# of related collections","extract":true},{"header":"# of related user comments","name":"# of related user comments","extract":true}],"delay":0,"tableDataRowSelector":"tr:nth-of-type(n+2)","tableHeaderRowSelector":"tr:nth-of-type(1)"}]}