Year Observations     Objects
1950            2          1 
1951            6          3 
1953            4          2 
1954            2          1 
1955            4          2 
1956            2          1 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978            8          3 
1981            4          2 
1982           12          6 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990           32         14 
1991          503        190 
1992          936        367 
1993         1666        609 
1994         2326        839 
1995         3429       1192 
1996         3576       1256 
1997         2329        794 
1998        23263       9808 
1999        14524       5569 
2000        40476      16796 
2001        43050      16693 
2002        32486      14522 
2003        61226      25381 
2004        47966      18396 
2005        85382      26251 
2006       110821      35412 
2007       204029      62571 
2008       125177      35627 
2009       101807      28609 
2010       118298      32859 
2011       177510      49090 
2012       164892      45567 
2013       256330      72386 
2014       610831     155951 
2015       730704     193577 
2016       587820     155880 
2017       603532     162527 
2018       397254     111125 
2019       932423     228512 
2020       687225     176102 
2021       895032     214271 
2022       664511     190068 
2023       603577     173794 
2024       220383      63678