Table:
text: Busiest airports in the United Kingdom by total passenger traffic
2006 Data
2006 Data
Rank_ Airport Total_Passengers _Change_2005_2006 International_Passengers Domestic_Passengers Transit_Passengers Aircraft_Movements Freight_Metric_Tonnes
1 London Heathrow 67527923 0.6% 61345841 5993386 188696 477048 1263128
2 London Gatwick 34163579 4.2% 30018783 4061562 83234 263363 211857
3 London Stansted 23687013 7.7% 21002260 2678092 6661 206693 224312
4 Manchester 22442855 0.2% 18601604 3522158 319093 229729 148957
5 London Luton 9425908 3.0% 7875084 1539745 11079 116131 17993
6 Birmingham Airport 9147384 2.5% 7532792 1523212 91380 119490 14681
7 Glasgow International 8848755 0.6% 4245338 4575124 28293 110034 6289
8 Edinburgh 8611345 1.8% 2743220 5863431 4694 126914 36389
9 Bristol 5757963 9.6% 4297696 1412526 47741 84583 32
10 Newcastle 5431976 4.4% 3624228 1783134 24614 81655 306

Question: How many airports ranked fourth among the UK's busiest airports by total passenger traffic in 2006?