export your data in Trello and use this script to covert the exported json to xls

trello_json_to_xls.rb

require 'json'
require 'spreadsheet'

if ARGV.size < 2
  puts 'Usage: ruby trello_to_csv.rb input.json output.xls'
  exit 1
end

@json_file = ARGV[0]
@xls_file = ARGV[1]

class Record
  attr_accessor :date,:description
  def initialize(date, description)
    @date = date
    @description = description
  end
end

def parse_records(raw)
  result = []
  dates = raw.sub(/^[^#]*#/, '')
  description = raw.sub(/#.*$/, '')
  dates.split('#').each do |date|
    result << Record.new(date.strip, description.strip)
  end
  result
end

json = JSON.parse(File.read(@json_file))
records = []
result_records = []

json['cards'].each do |card|
  name = card['name']
  records += parse_records(name)
end

records.sort! do |x,y|
  x.date <=> y.date
end

records.each do |record|
  puts "#{record.date},#{record.description}"
  result_records << record if result_records.size == 0
  if result_records[-1].date == record.date
    result_records[-1].description += ("; " + record.description)
  else
    result_records << record 
  end
end

## Convert to xls file
book = Spreadsheet::Workbook.new
sheet = book.create_worksheet

header_format = Spreadsheet::Format.new(
  :weight => :bold
)

sheet.row(0).default_format = header_format
sheet.row(0).replace(['Date', 'Description'])

result_records.each_index do |i|
  row = []
  row << result_records[i].date << result_records[i].description
  sheet.row(i+1).replace(row)
end

book.write(@xls_file)