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         2329        840 
1995         3799       1316 
1996         3578       1257 
1997         2335        796 
1998        23277       9814 
1999        14545       5578 
2000        40526      16819 
2001        43135      16731 
2002        32594      14571 
2003        61426      25463 
2004        48177      18478 
2005        85895      26397 
2006       111340      35565 
2007       205164      62877 
2008       126274      35921 
2009       102778      28873 
2010       119306      33121 
2011       179136      49538 
2012       166329      46025 
2013       257433      73101 
2014       641299     163496 
2015       744920     197668 
2016       573396     153010 
2017       611502     163979 
2018       404649     113429 
2019       941049     230073 
2020       694836     178226 
2021       902074     216079 
2022       669585     191503 
2023       610310     175695 
2024       201669      58022