The following data give the worldwide number of fatal airline accidents of commercially scheduled air transports in the years from 1997 to 2005.
|
Year
|
1997 1998
|
1999
|
2000
|
2001
|
2002
|
2003
|
2004
|
2005
|
|
Accidents
|
25 20
|
21
|
18
|
13
|
13
|
7
|
9
|
18
|
Find the sample variance of the number of accidents in these years.