text: const mongoose = require('mongoose');
  
  const statisticDaySchema = new mongoose.Schema({
      totalTransactionFees: {
          sum: {
              type: String,
              required: true,
              default : '0'
          },
          count: {
              type: String,
              required: true,
              default : '0'
          }
      },
      numberOfTransactions: {
          count: {
              type: String,
              required: true,
              default : '0'
          }
      },
      totalOutputVolume: {
          sum: {
              type: String,
              required: true,
              default : '0'
          }
      },
      totalBlocks: {
          count: {
              type: String,
              required: true,
              default : '0'
          }
      },
      difficulty: {
          sum: {
              type: String,
              required: true,
              default : '0'
          },
          count: {
              type: String,
              required: true,
              default : '0'
          }
      },
      stake: {
          sum: {
              type: String,
              required: true,
              default : '0'
          }
      },
      supply: {
          sum: {
              type: String,
              required: true,
              default : '0'
          }
      },
      date: {
          type: Date,
          required: true,
          index: true
      }
  }, {
      timestamps: {
          createdAt: 'created_at',
          updatedAt: 'updated_at'
      }
  });
  
  const StatisticDay = mongoose.model('StatisticDay', statisticDaySchema);
  
  module.exports = StatisticDay;