HF Beacons and the Reverse Beacon Network, 2009 to 2017

I initially posted about the RBN and HF beacon stations here.

As I did there, I here include a table of the twenty fixed-frequency stations most often posted by the RBN, this time extending the period covered to the period between the inception of the RBN (in 2009) to the end of 2017.

Position	Station	Frequency (kHz)	Number of Posts	Earliest Post	Latest Post
1	I1MMR	7026	295,176	20090409	20171231
2	4U1UN	14100	219,963	20140618	20171231
3	AA1K	1821	211,640	20090221	20171231
4	I1MMR	7027	205,788	20090308	20171231
5	W0ERE/B	10129	198,641	20111002	20171231
6	4X6TU	14100	188,898	20110215	20171231
7	EW7LO	7008	173,511	20090221	20171227
8	W9ZN	7034	167,343	20090225	20171231
9	DK0WCY	10144	157,182	20100601	20171231
10	SK6RUD	10133	156,067	20100720	20160421
11	4X6TU	21150	148,571	20110303	20171231
12	W0ERE	10129	135,752	20100308	20170903
13	YV5B	14100	135,464	20131228	20171231
14	4X6TU	18110	131,123	20120127	20171231
15	W6WX	14100	125,519	20111116	20171231
16	RR9O	14100	117,224	20111221	20171231
17	IK1HGI/B	7039	114,336	20120516	20170616
18	N4BP	14022	111,417	20090225	20171230
19	DK0WCY	3579	110,816	20111027	20171231
20	4U1UN	18110	109,522	20140618	20171231

Notes:

1. Frequencies are rounded to the nearest kHz;
2. The first and fourth positions are occupied by what is really the same station, which appears to transmit on 7026.5 kHz;
3. Positions 5 and 12 appear to be occupied by a single station, using alternative versions of a single callsign;
4. I am unsure how the U.S. stations in the list can be legal, since the FCC's regulations appear to limit [unattended] HF beacons to a portion of 10m;
5. FCC regulations also appear to disallow the use of the "/B" indicator as used by station number 5, as the B series is allocated to China.
6. It is my memory that the original HF beacons were all located on 28 MHz, so that listeners could be made aware of an opening. It is noticeable that not a single one of the stations on the list above is on 10m: the vast majority are on bands that can reasonably be expected to support some kind of non-local propagation at almost all times (which is probably the very reason that they are posted by the RBN so often -- but one does wonder what the putative purpose of such a beacon is);
7. Of the twenty stations in the list, all but one were still active as of (or close to) the end of 2017.