Extracting ICMP Output for Plotting

Dear,

I want to perform a plotting using xgraph, and the plotting data (ping.txt) is as below. For the graph I just want to plot the time for x-axis (line count) and the RTT for y-axis (time in ms). Below are script i write for that purpose but it seen did not work. Any guide for me because i think the script is wrong. The example of plot is about like this:

ping.txt
-------------------------------------------------------------
64 bytes from 192.168.1.100: icmp_seq=0 ttl=255 time=0.712 ms
64 bytes from 192.168.1.100: icmp_seq=1 ttl=255 time=0.620 ms
64 bytes from 192.168.1.100: icmp_seq=2 ttl=255 time=0.698 ms
64 bytes from 192.168.1.100: icmp_seq=3 ttl=255 time=0.662 ms
64 bytes from 192.168.1.100: icmp_seq=4 ttl=255 time=0.649 ms
-------------------------------------------------------------

Intended plot.txt
-----------------
1 0.712
2 0.620
3 0.698
4 0.662
5 0.649
-----------------

I have a feeling that this is not all you need - but anyway:

$ cat ping.txt
64 bytes from 192.168.1.100: icmp_seq=0 ttl=255 time=0.712 ms
64 bytes from 192.168.1.100: icmp_seq=1 ttl=255 time=0.620 ms
64 bytes from 192.168.1.100: icmp_seq=2 ttl=255 time=0.698 ms
64 bytes from 192.168.1.100: icmp_seq=3 ttl=255 time=0.662 ms
64 bytes from 192.168.1.100: icmp_seq=4 ttl=255 time=0.649 ms
$
$ awk '{split($7,a,"="); print NR, a[2];}' ping.txt
1 0.712
2 0.620
3 0.698
4 0.662
5 0.649