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         4071       1407 
1996         3581       1258 
1997         2331        795 
1998        23293       9820 
1999        14561       5585 
2000        40577      16843 
2001        41574      16211 
2002        32666      14603 
2003        61599      25529 
2004        48341      18543 
2005        86204      26490 
2006       111642      35654 
2007       205798      63056 
2008       126772      36056 
2009       103292      29013 
2010       119842      33259 
2011       180093      49797 
2012       167196      46263 
2013       259166      73577 
2014       644635     164414 
2015       749038     198795 
2016       575304     153549 
2017       612573     163900 
2018       406397     113883 
2019       932726     227562 
2020       696943     178929 
2021       931363     222781 
2022       675067     193112 
2023       613557     176633 
2024       155956      44632