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         1669        610 
1994         2326        839 
1995         3790       1313 
1996         3578       1257 
1997         2335        796 
1998        23274       9813 
1999        14540       5576 
2000        40504      16808 
2001        43095      16712 
2002        32575      14563 
2003        61367      25439 
2004        48096      18448 
2005        85739      26356 
2006       111155      35510 
2007       204896      62806 
2008       125947      35832 
2009       102516      28802 
2010       119053      33054 
2011       178723      49423 
2012       166005      45903 
2013       256896      72859 
2014       641526     163260 
2015       745620     197337 
2016       573669     153030 
2017       611319     163885 
2018       405415     113286 
2019       943566     230995 
2020       693196     177770 
2021       900110     215575 
2022       668114     191091 
2023       608505     175185 
2024       200723      57759