t    sales
 1    4.8
 2    4.0
 3    5.5
 4   15.6
 5   23.1
 6   23.3
 7   31.4
 8   46.0
 9   46.1
10   41.9
11   45.5
12   53.5
13   48.4
14   61.6
15   65.6
16   71.4
17   83.4
18   93.6
19   94.2
20   85.4
21   86.2
22   89.9
23   89.2
24   99.1
25  100.3
26  111.7
27  108.2
28  115.5
29  119.2
30  125.2
31  136.3
32  146.8
33  146.1
34  151.4
35  150.9