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          512        193 
1992          936        367 
1993         1669        610 
1994         2329        840 
1995         4029       1393 
1996         3581       1258 
1997         2331        795 
1998        23291       9819 
1999        14561       5585 
2000        40573      16841 
2001        41564      16208 
2002        32663      14602 
2003        61589      25525 
2004        48328      18538 
2005        86186      26485 
2006       111631      35650 
2007       205753      63044 
2008       126747      36049 
2009       103271      29007 
2010       119811      33251 
2011       180029      49780 
2012       167132      46247 
2013       259102      73559 
2014       644510     164382 
2015       748954     198772 
2016       575293     153547 
2017       613049     164002 
2018       406260     113846 
2019       933383     227751 
2020       696813     178894 
2021       905643     217122 
2022       674582     192974 
2023       613586     176634 
2024       159025      45561