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         4149       1433 
1996         3584       1259 
1997         2334        796 
1998        23296       9821 
1999        14569       5588 
2000        40607      16857 
2001        41618      16230 
2002        32691      14614 
2003        61644      25548 
2004        48379      18559 
2005        86273      26511 
2006       111768      35692 
2007       206049      63124 
2008       126974      36110 
2009       103410      29046 
2010       119993      33301 
2011       180395      49878 
2012       167570      46364 
2013       259725      73737 
2014       645560     164648 
2015       749775     198995 
2016       576261     153819 
2017       611532     163674 
2018       406827     114000 
2019       930789     227013 
2020       698097     179218 
2021       959813     228169 
2022       676620     193556 
2023       614785     176964 
2024       156402      44781