Not sure why people are suggesting databases for a task that can be done by a one liner on a file of 132000 lines in under 1 second?

[21:23:36.53] C:\test>
perl -anlE"$s{$F[1]}+=$F[2];++$n{$F[1]}}{say $_,':',$s{$_}/$n{$_} for 
+sort keys%s" junk.dat
0101:4.563
0102:4.602
0103:4.632
0104:4.557
0105:4.515
0106:4.605
0107:4.59
0108:4.501
0109:4.441
0110:4.439
0111:4.542
0201:4.611
0202:4.461
0203:4.627
0204:4.447
0205:4.537
0206:4.434
0207:4.421
0208:4.412
0209:4.58
0210:4.416
0211:4.431
0301:4.444
0302:4.73
0303:4.541
0304:4.564
0305:4.524
0306:4.596
0307:4.618
0308:4.352
0309:4.331
0310:4.489
0311:4.436
0401:4.6
0402:4.425
0403:4.455
0404:4.451
0405:4.482
0406:4.601
0407:4.677
0408:4.307
0409:4.59
0410:4.528
0411:4.366
0501:4.602
0502:4.471
0503:4.5
0504:4.431
0505:4.372
0506:4.543
0507:4.441
0508:4.499
0509:4.476
0510:4.512
0511:4.575
0601:4.425
0602:4.536
0603:4.522
0604:4.585
0605:4.495
0606:4.425
0607:4.595
0608:4.48
0609:4.553
0610:4.528
0611:4.578
0701:4.38
0702:4.648
0703:4.583
0704:4.409
0705:4.575
0706:4.423
0707:4.352
0708:4.599
0709:4.372
0710:4.564
0711:4.39
0801:4.408
0802:4.51
0803:4.52
0804:4.412
0805:4.581
0806:4.469
0807:4.614
0808:4.632
0809:4.387
0810:4.533
0811:4.403
0901:4.314
0902:4.612
0903:4.463
0904:4.481
0905:4.643
0906:4.454
0907:4.343
0908:4.459
0909:4.593
0910:4.527
0911:4.545
1001:4.655
1002:4.456
1003:4.585
1004:4.536
1005:4.577
1006:4.441
1007:4.648
1008:4.549
1009:4.464
1010:4.696
1011:4.493
1101:4.548
1102:4.534
1103:4.646
1104:4.522
1105:4.522
1106:4.549
1107:4.563
1108:4.439
1109:4.539
1110:4.497
1111:4.531
1201:4.486
1202:4.471
1203:4.54
1204:4.428
1205:4.517
1206:4.506
1207:4.413
1208:4.49
1209:4.418
1210:4.475
1211:4.483
Date:0

[21:23:37.63] C:\test>wc -l junk.dat
 132001 junk.dat
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