Explorer quest rune count

I see people saying the probability of getting a rune has gone down. I decided to get actual stats, not just the anecdotal evidence people are going by.

Started @ 2424 quests

2427 - Rune S
2449 - Rune W
2456 - Rune M
2474 - Rune S
2500 - Rune M
2507 - Rune P
2512 - Rune G
2518 - Rune M
2522 - Rune A
2533 - Rune M
2542 - Rune I
2562 - Rune B
2592 - Rune K
2605 - Rune Z
2620 - Rune AE
2656 - Rune E
2671 - Rune R
2672 - Rune U
2681 - Rune H
2725 - Rune L
2741 - Rune G
2747 - Rune Q
2751 - Rune P
2780 - Rune D
2787 - Rune C
2788 - Rune R
2793 - Rune D
2849 - Rune F
2867 - Rune M
2882 - Rune K
2895 - Rune U
2898 - Rune M
2900 - Rune Q
2941 - Rune O
2942 - Rune S
3009 - Rune P
3022 - Rune L
3027 - Rune AE
3059 - Rune H
3073 - Rune F
3086 - Rune I
3093 - Rune T
3100 - Rune U
3106 - Rune J
3151 - Rune N
3185 - Rune P
3187 - Rune J

763 quests = 47 runes

average quest/rune = 16.23